// Browser capabilities detection ---
// - assume only IE4+ and NAV6+ can do image resizing, others redirect to low 
if (useHigh) {
    //-- it's all good ---
} else {
    // -- any other browser we go low-tech and reload whole page ---
    window.location.href = slideShowLow;
}

function stopOrStart() {
    if (onoff) {
	stop();
    } else {
	play();
    }
}

function toggleLoop() {
    if (loop) {
	loop = 0;
    } else {
	loop = 1;
    }
}

function changeElementText(id, newText) {
    element = document.getElementById(id);
    element.innerHTML = newText;
}

function stop() {
    changeElementText("stopOrStartText", "<img src=Start.jpg width=65 height=21 align=top style='position: relative; top: 0; border: 1 ridge #D3D3D3; padding: 1'>");

    onoff = 0;
    status = "Klik op [Start] om de diavoorstelling te beginnen.";
    clearTimeout(timer);

}

function play() {
    changeElementText("stopOrStartText", "<img src=Stop.jpg width=65 height=21 align=top style='position: relative; top: 0; border: 1 ridge #D3D3D3; padding: 1'>");

    onoff = 1;
    status = "De diavoorstelling is bezig...";
    go_to_next_photo();
}

function changeDirection() {
    if (direction == 1) {
	direction = -1;
	changeElementText("changeDirText", "<img src=Vooruit.jpg width=65 height=21 align=top style='position: relative; top: 0; border: 1 ridge #D3D3D3; padding: 1'>");
    } else {
	direction = 1;
	changeElementText("changeDirText", "<img src=Achteruit.jpg width=65 height=21 align=top style='position: relative; top: 0; border: 1 ridge #D3D3D3; padding: 1'>");
    }
    preload_next_photo();

}

function change_transition() {
    current_transition = document.TopForm.transitionType.selectedIndex;
}

function preload_complete() {
}

function reset_timer() {
    clearTimeout(timer);
    if (onoff) {
	timeout_value = document.TopForm.time.options[document.TopForm.time.selectedIndex].value * 1000;
	timer = setTimeout('go_to_next_photo()', timeout_value);
    }
}

function wait_for_current_photo() {

    /* Show the current photo */
    if (!show_current_photo()) {

	/*
	 * The current photo isn't loaded yet.  Set a short timer just to wait
	 * until the current photo is loaded.
	 */
	status = "De dia wordt opgehaald...(" + current_location + " of " + photo_count +
		").  Please Wait..." ;
	clearTimeout(timer);
	timer = setTimeout('wait_for_current_photo()', 500);
	return 0;
    } else {
	status = "De diavoorstelling is bezig...";
	preload_next_photo();
	reset_timer();
    }
}

function go_to_next_photo() {
    /* Go to the next location */
    current_location = next_location;

    /* Show the current photo */
    if (!show_current_photo()) {
	wait_for_current_photo();
	return 0;
    }

    preload_next_photo();
    reset_timer();
}

function preload_next_photo() {
    
    /* Calculate the new next location */
    next_location = (parseInt(current_location) + parseInt(direction));
    if (next_location > photo_count) {
	next_location = 1;
	if (!loop) {
	    stop();
	}
    }
    if (next_location == 0) {
        next_location = photo_count;
	if (!loop) {
	    stop();
	}
    }
    
    /* Preload the next photo */
    preload_photo(next_location);
}

function show_current_photo() {
    /*
     * If the current photo is not completely loaded don't display it.
     */
    if (!images[current_location] || !images[current_location].complete) {
	preload_photo(current_location);
	return 0;
    }
    
    /* transistion effects */
    if (browserCanBlend){
	var do_transition;
	if (current_transition == (transition_count)) {
	    do_transition = Math.floor(Math.random() * transition_count);
	} else {
	    do_transition = current_transition;
	}
	document.images.slide.style.filter=transitions[do_transition];
	document.images.slide.filters[0].Apply();
    }

    document.slide.src = images[current_location].src;
    setCaption(photo_captions[current_location]);

    if (browserCanBlend) {
	document.images.slide.filters[0].Play();
    }

    return 1;
}

function preload_photo(index) {

    /* Load the next picture */
    if (pics_loaded < photo_count) {

	/* not all the pics are loaded.  Is the next one loaded? */
	if (!images[index]) {
	    images[index] = new Image;
	    images[index].onLoad = preload_complete();
	    images[index].src = photo_urls[index];
	    pics_loaded++;
	}
    } 
}

function setCaption(text) {
    changeElementText("caption", text);
}